Jooja to the rescue once again!
It took some reworking but that did the trick:
1.)Created NURBS base banner, added sine deformer to create desired waving
2.) Set sine envelope to 0 and duplicated base banner (now flat)
3.) used flat banner as blend target, with blend set to 1 this flattened the base banner despite the since deformer.
4.) editing weights in the component editor, I was able to remove the blend shape influence fromall but the top CV's, creating the "flat" top I wanted.
Thanks again, jooja!
my hero\